Plankton facts

Plankton is the great mass of floating and drifting animals and
plants found in the sea and fresh water. Most of them are so small
that they can be seen only with a microscope. They are suspended in
the water much like the dust particles we can sometimes see in a
beam of light. Below you can see some plankton facts

The
planktonic plants are extremely important to the life of the sea,
because they are responsible for making nearly all the food material
in the sea. They do this by the process called photosynthesis (see
Photosynthesis interesting facts). The tiny animals of the marine
plankton graze on the plants. They in turn are preyed on by larger
animals (such as herring) which are in their turn eaten by larger
fish (such as cod). In fact, some of the sea's largest creatures -
some whales and sharks - eat only plankton.

Plankton facts:

The picture shows some of the many tiny plants and animals that live in the sea. The marine plankton here includes dinoflagellates (top and bottom left), diatom (top right) and a strange sea snail (bottom center)

Plankton facts:

One of kinds of a marine plankton - the plants of the
sea plankton are called phytoplankton

Planktonic plants live only in the upper levels of the water
because they must have sunlight to carry on photosynthesis. Not
enough light penetrates below about 150 feet in most parts of the
sea for photosynthesis. Planktonic animals may, however, swim down
several hundred feet during daylight, but then float to the surface
again at night.

Some more
plankton facts: the plants of the marine plankton are
called phytoplankton; the animals, zooplankton. All phytoplankton
come from the large group of
plants called algae. The main types are
diatoms, which range in size from 1/2,500 to 1/250 of an inch. They
are single-celled, and each consists of an irregular sac of
protoplasm (living jelly) surrounded by a delicate, transparent box
or shell.

Diatoms occur in a great variety of beautiful shapes, often with
fine spines. The zooplankton consists of members of many animal
groups, including protozoans (single-celled animals), jellyfish,
worms and snails.

But the largest groups are crustaceans, particularly the type
known as copepods, or oar-footed creatures. These all spend their
entire life as plankton. Other sea animals, such as fish, crabs,
barnacles, starfish and many mollusks, are planktonic only as eggs
or when young. They then settle on the sea-bed, or join the members
of the nekton (the active swimming group).